Railway switch operating apparatus



March 18, 1941. K. J. J. McsowAN RAILWAY SWITCH OPERATING API'ARATUSFiled July 24, 1946 2 Sheets-Sheet 1 II 4m W w J j H 0 on c o I m 7 A hLM 0 occooo U C v m M @L in INVENTOR H15 ATTORNEY Patented Mar. 18, 1941PATENT OFFICE RAILWAY SWITCH OPERATING APPARATUS Kenneth J. J. McGowan,Pittsburgh, Pa., assignor to The Union Switch & Signal Company,Swissvale, Pa., a corporation of Pennsylvania Application July 24, 1940,Serial No. 347,269

4 Claims.

My invention relates to railway switch operating apparatus, andparticularly to manually con.- trolled switch operating apparatus forspring switches.

More particularly, my present invention relates to railway switchoperating apparatus of the type described and claimed in Letters Patentof the United States No. ,9 ranted to Herbert L. Bone on October 16,1934. {In the said Bone apparatus, a switch is arranged to be movedbetween two spring biased extreme positions through the medium of amanually operated switch throwing mechanism including a reciprooablerack bar or motion plate, and to be looked a in one extreme position bymeans of a locking plunger biased to a locking position. The lookingplunger is operatively connected with the rack bar in such manner thatmovement of the rack bar, in the direction to move the switch away fromsaid one extreme position, will cause the locking plunger to be moved toits unlocking position prior to any movement of the switch points. Thelocking plunger is also operatively connected with linkage which, whenthe switch occupies its locked position and a train starts to trail theswitch, is mechanically actuated by a train in a manner to move thelocking plunger to its unlocking position before sufiicient force isexerted on the switch points by the train to overcome the force of thespring means which biases the switch points to said one extremeposition.

One object of my present invention is to ima prove the construction ofthe locking mechanism and the means for operatively connecting it withthe rack bar and the lock releasing linkage in apparatus of the typedescribed in the said Bone patent.

Another object of my invention is to provide apparatus for looking aspring switch in one extreme position for facing point moves over theswitch and for automatically unlocking the switch when a train trailsthe switch, which apparatus may be used in connection with the switchthrowing mechanism described and claimed in Letters Patent of the UnitedStates No. 2,184,870, granted to- Herbert L. Bone and myself on December26, 1939, 'for Railway switch operating mechanisms.

A further object of my invention is the provision in apparatus of thetype described of improved means for biasing the locking plunger to itslocking position, which improved means requires less spac-e, is cheaperto construct, and

exerts a stronger biasing force than the corresponding biasing meansshown and described in the said Bone Patent No. 1,976,827.

According to my invention, a lock bar extends lengthwise of the switchthrowing apparatus and cooperates at one end with a lock rod secured tothe switch points to lock the switch in its one extreme position. Theother end of the lock bar is pinned to a piston slidably mounted in aspring cage comprising part of a. biasing device for biasing the lockbar to its locking position. The spring cage, in turn, is slidablymounted in a cylindrical housing secured to one end of the apparatuscasing and is operatively connected. at its inner end to the rack bar ofthe switch throwing mechanism by means of two spaced arms connected attheir free ends by a depending web which extends into a transverse slotprovided in the upper face of the rack bar. The piston of the biasingdevice is provided with a tubular extension having an annular inturnedshoulder at one end, and this extension slidably receives the head of aplunger bolt comprising parts of the lock releasing linkage, tooperatively connect the locking plunger with the lock releasing linkage.

Other objects and characteristic features of my invention will becomeapparent as the description proceeds.

I shall describe one form of apparatus em- 3 bodying my invention, andshall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. l is a top plan view showing a springswitch A controlled 3 by a switch operating mechanism B constructed inaccordance with my invention. Fig. 2 is an enlarged top plan View of theswitch operating mechanism B shown in Fig. 1, with the main coverremoved and a part of the casing broken away to better illustrate theconstruction of the various operating parts of the mechanism. Fig. 3 isa longitudinal sectional view of the mechanism shown in Fig. 2.

Similar reference characters refer to similar parts in all three views.

Referring first to Fig. 1, the reference character A designates arailway switch comprising, as usual, two fixed rails l and la and twpmovable rails 2 and 2a. The fixed rails l and lo arel; laid on tieplates 3 and are secured to crossties 4 in the usual manner. The movablerails 2 and 2a are fastened together by a front rod 5, a head rod 6, abridle rod '1 and a tie rod 8, and

may be moved into a normal or a reverse posi- 55 tion by means of aswitch operating mechanism B which is connected with the head rod 6through the medium of an operating rod 9 and a spring connecting rod C.When the switch occupies its normal position in which position it isshown in Fig. l, the movable rail 2 engages the fixed rail I, and themovable rail 2a is spaced a slight distance from the fixed rail I. Whenthe switch is reversed, however, the movable rail 2a then engages thefixed rail Ia, and the movable rail 2 is spaced from the fixed rail Thespring connecting rod C may be of any suitable type, but in thewell-known form here illustrated, this connecting rod is similar in allrespects to the spring connecting rod C shown and described in the BonePatent No. 1,976,827 referred to hereinbefore. For purposes of thepresent disclosure, it is sufficient to point out that this connectingrod comprises a cylindrical housing Ii) which is secured to the head rod6, and which slidably receives a spring rod M. The spring rod i4 isattached at one end to the operating rod 9, and is biased, by suitablespring means enclosed in the housing In, to an intermediate positionrelative to the housing in such manner that movement of the spring rodin either direction from this intermediate position will cause thespring means to become compressed and exert a yieldable force on thehousing which tends to cause it, and hence the switch points, to followthe movement of the spring rod.

The head rod 6 is also connected by means of an adjustable link If withthe piston rod I6 of a bufling device D. This bufiing device may also bei of any suitable type, but, as here shown, this buffing device issimilar in all respects to the bufling device shown and described inLetters Patent of the United States No. 1,869,604, granted to William C.McWhirter on August 2, 1932, for Buliing devices for railway switchesand the like. It is believed, therefore, that for purposes of thepresent disclosure the following brief description of the bufling deviceD will suflice. This buffing device includes, in addition to the pistonrod l6, a cam shaft extending into the case of the device andcontrolling a valve mechanism not shown. Attached to the outer end ofthe cam shaft i1 is a crank 18 which is connected by ;a link IS with thespring rod l4 of the spring connecting rod C. If, when the movable rails2 and 2a of the switch A are in their normal positions, as shown in Fig.1, they are moved to their reverse positions by the mechanism B, the

piston rod IE will be moved into the device and the cam shaft will berotated in a clockwise direction as viewed from the left in Fig. l. Theconstruction of the device is such that, under these conditions, thepiston rod IE will be permitted to move with substantially noresistance, and the bufiing device will therefore exert practically noretarding action on the movable rails. Conversely, if the movable railsare moved from their reverse positions to their normal positions by themechanism B, the piston rod ||5 will be moved outwardly and the camshaft i! will be rotated in a counterclockwise direction, as viewed fromthe left in Fig. 1, but due to the construction of the device, noretarding action will again take place. If, however, when the movablerails are in either extreme position, a train trails the switch, the camshaft I! will remain stationary, and under these conditions, the actionof the device is such that the movement of the movable rails away fromthe positions which they previously occupied will be unresisted by thebuffing device, but that, when the movable rails are being restored tothe positions which they previously occupied by the spring means of thespring connecting rod C, the buffing device will act to retard thislatter movement.

The switch operating mechanism B is mounted on one end of a tie strap 20which is secured to the ties adjacent the outer side of the rail and asbest seen in Figs. 2 and 3, this mechanism in the form here showncomprises a suitable casing 2| which encloses the operating parts of themechanism and which is closed at its upper end by a removable cover 22.in place at its right-hand end by means of a U- bolt 23 which overliesfingers 22a cast on the cover, and at its left-hand end by an adjustablehasp 24. This structure for securing the cover in place is described andclaimed in the copending application for Letters Patent of the UnitedStates, Serial No. 287,116, filed by Herbert L. Bone and myself on July28, 1939, for Cover securing means for casings.

Located within the casing I0 is a rack bar or motion plate 25 which isguided to slide longitudinally in a direction parallel to the track bymeans of guide rollers 26 and 21 secured to the underside of the rackbar adjacent its opposite ends and cooperating with a guideway 28provided in the bottom wall of the casing. The rack bar 25 has rackteeth 29 formed on its upper surface on one side of the center line.These rack teeth mesh with a segment gear 30 mounted on a square shaft3|, which shaft, in turn, is mounted at its ends in bearing sleeves 32and 33 journaled in bosses 34 and 35 formed in the side walls of thecasing Ill. Secured to the outer end of the shaft 3| by means of athrough bolt 3'1 is a hand lever 38 which serves as a means forreciprocating the rack bar between its two extreme positions.

A roller 40 is secured to the underside of the .motion plate 25 adjacentone side thereof at a point equally spaced from the rollers 26 and 21,and this latter roller cooperates with cam faces 4| and 42 formed on anescapement crank 43 (see Fig. 2). The escapement crank 43 is formedintegrally with the upper end of a switch actuating shaft 44, the shankof which is provided with two bearing surfaces 45 and 46 separated by anenlarged portion 41. The bearing surfaces 45 and 46 are journaled invertically aligned bearings 48 and 49 formed respectively in the bottomwall of the casing 2|, and in a depending stirrup 50 which is providedon the underside of the casing, and adjustably secured to the enlargedportion 4'! of the shaft is a switch operating arm 50a. which ispivotally attached to the free end of the operating rod 9.

The portion of the switch operating mechanism thus far described isidentical with that shown and described in United States Letters PatentNo. 2,184,870 referred to hereinbefore.

A look bar 5| extends longitudinally of the casing 2| directly above themotion plate 25, and cooperates at its left-hand end, as viewed in Figs.2 and 3, with a lock rod L which is slidably mounted in a transverseguideway 2 la formed in the casing 2|. The lock rod L, in the form hereshown, is of standard construction, and is adjustably secured at one endto the front rod 5 of the switch A. Formed in the lock rod is a notch 48so disposed that it will align with the lock bar 5| when and only whenthe switch A oc- The cover 22 is held cupies the extreme position.inwhich it is shown in Fig. 1.

The right-hand end of the lock bar as viewed in Fig. 3, extends withconsiderable clearance through an opening 52 formed in an. end plate 55comprising part of a spring cage 54, and is pinned to a piston 55reciprocably mounted within the spring cage. The spring cage is slidablymounted in a cylindrical housing 52 secured to one end of the casing Zl, and comprises, in addition to the end plate 53, a tube 55 which ispartly closed at one end by the end plate, and a tube 51 of smallerdiameter than the tube 55 screwed into the tube 55 at the end oppositeto the end plate. The tube 57 is partly closed at its outer end by anend plate 55 brazed or otherwise secured to the tube, and this end plateis flattened on two sides for the reception of a suitable tool tofacilitate screwing the tube 5! into the tube 55. A screw 59 is threadedinto a tapped radial hole in the end plate 58, and has its head disposedin a slot 50 formed in the end of the tube iii to lock the two tubesinthe proper relative longitudinal positions. The spring cage houses acompressed coil spring 6!, one end of which abuts against the piston 55and the other end of which abuts against the end plate 58. This springis relatively stiff requiring considerable force to compress it, and thefunction of the inner tube 5? and associated end plate 55 is to providea convenient means for compressing this spring during assembly of theparts. It will be apparent that the spring 6! serves to constantly biasthe piston toward the position in which it engages the end plate 53. Thespring 5.! is centered at the end which engages the piston by a tubularextension 63 formed on the piston, and the function of which will bemade clear presently.

Formed on the end plate 55 of the spring cage 541 on opposite sides ofthe lock bar 5! are two spaced arms 55, the free ends of which areconnected together by a depending web 55 disposed underneath the lockbar. This web extends into a transverse slot 6'! provided in the upperface of the rack bar 125, and serves as a means for operativelyconnecting the spring cage, and hence the lock bar 5!, with the rack barfor a purpose which will be made clear presently.

The parts are so proportioned that when the rack bar 25 is in itsleft-hand extreme position, as shown in Figs. 2 and 3, the biasingspring 6! will tend to drive the look bar 5! to an extreme positionwhich is beyond the desired locking position. The locking device isprevented from moving beyond the desired locking position under theseconditions, however, by linkage which connects the lock bar with the tierod 8.

As here shown, this linkage includes a plunger bolt W provided with around head I! which is slidably mounted in the previously describedtubular extension 55 formed on the piston 55, and which. at timesengages an annular inturned shoulder 53a formed on the right-hand end ofthe extension. The shank of the plunger bolt extends with clearancethrough an opening 53a provided in the end plate 58 of the spring cage54, and through a bushing I? provided in the outer end of the housing62, and is adjustably connected at its outer end by means of aturnbuckle it (see Fig. l) with one end of a link M, the opposite end ofwhich link is pivotally connected With the long arm a of a bell cranklever 15. The bell crank lever 75 is pivotally supported in a crankstand it, and has. its short arm l5bpivfit otally connected with one endof an operating rod Ti. The other end of the operating rod 1'! isconnected with the previously described tie rod 5 by means of a standardswitch basket 18. The tie rod 3 may be located at any suitable location,but will preferably be located approximately half- Way between the heeland the point of the switch. The base 19 of the crank stand 16 issecured both to a gauge plate ill] and to the tie strap upon which themechanism B is mounted, and it will be apparent, therefore, that anyloss of adjustment between the parts due to creepage of the ties isprevented. The plunger bolt it, turnbuckle !3, link M, bell crank leveroperating rod Tl, spring basket 18 and tie rod 8 all constitute meansfor effecting the unlocking of the switch during a trailing move, aswill be made clear presently.

The lock bar 5!, adjacent the end which cooperates with the lock rod L,is slidably supported in a bracket 8!, which bracket also serves as ameans for supporting a suitable circuit controller not shown. Thecontacts of this circuit controller are controlled jointly by the lockbar 5! and by a point detector rod 1?, and this circuit controller may,for example, be similar to that described and claimed in the previouslyreferred to Letters Patent of the United States No. 2,134,870. The pointdetector rod P is slidably mounted in the casing 2!, and is attached bymeans of alink 82 and a bolt member 55 with the movable rail 2 of theswitch A in the usual and well-known manner.

The operation, as a whole, of the apparatus is as follows: When the handthrow lever is rotated to its normal extreme position in which'it isshown in the drawings, the rack bar 25 is moved to its extreme left-handor normal position in which it is shown in Figs. 2 and 3, and underthese conditions the escape-merit crank 13 is held in its clockwiseextreme position as viewed. in Fig. 2 by engagement of the roller 55with the cam surface 4! of the escapement crank. When the crank 43occupies this extreme position, a force is exerted on the movable rails2 and Zia of the switch through the medium of the spring connecting rodC, which force yieldably holds the movable rails in their normal extremepositions in which they are shown in Fig, 1. When the movable rails arein their normal positions, the notch 48 in the lock rod L aligns withthe lock bar 5!, and the lock bar is therefore moved. by the biasingspring 55 to its locking position in which the lock bar enters the notchit, thus securely locking the switch points in their normal positions.

When it is desired to reverse the switch, the hand-thrown lever 38 isrotated from the extreme position in which is is shown in Fig, 1 to itsopposite extreme position. This movement of the lever causes the rackbar 125 to move from its extreme left-hand position, as viewed in Figs.2 and 3, to its extreme right-hand position. This movement of the rackbar, in turn, is transmitted through the slot til, web 55, arms 85 andend plate 53 to the spring cage 55 which causes end plate 53 to moveinto engagement with the piston 55 as soon as the rack bar has moved ashort distance. As a result, as the rack bar continues to move, the lockbar 5! is moved with the rack bar, thus withdrawing it from engagementwith the notch t8 in the lock rod L, and hence unlocking the movablerails 2 and The parts are so proportioned that While the lock bar isbeing withdrawn from engagement with the notch 48 in the lock rod, theroller 40 on the rack bar will continue to engage the escapement crank43 at the cam face 4| which during this movement is parallel to thedirection of movement of the rack bar, and as long as this portion ofthe cam face is engaging the roller, the crank 43 will remainstationary. It follows, therefore, that during that portion of themovement of the rack bar which is necessary to unlock the movable railsof the switch, no force is exerted on these rails tending to reversethem. As soon, however, as this first part of the movement of the motionplate has been completed, the roller 40 then moves into engagement withthe cam face 42 of the escapement crank which causes the crank to berotated in a counterclockwise direction, as viewed in Fig. 2, and as aresult the rails are then moved to their reverse positions. Aspreviously pointed out, when the rails are being moved to their reversepositions by the mechanism B, the piston rod l5 of the buffing device Bis moved into the device, and the cam shaft I! is rotated in a clockwisedirection, as viewed from the left in Fig. 1, but due to theconstruction of this device, the device oifers substantially noresistance to the movement of the rails under these conditions. Itshould be noted that as long as the movable rails remain stationary, theplunger bolt 10 remains fixed, so that during the first part of themovement of the motion plate, the shoulder 63a will move out ofengagement with the head H of the plunger bolt. As soon as the movablerails have started to move, however, the resultant movement of the tierod 8 acting through the switch basket 78, operating rod 'i'l, bellcrank lever 15 and link 14 causes the plunger bolt to move in the samedirection as the rack bar is moving, although the time of motion andrate of motion of the plunger bolt will bear no direct relation to themovement of the rack bar. During the final movement of the rack bar, theroller ll! moves along the straight portion of the cam surface 42 tosuch a position that any tendency of the switch actuating shaft torotate in a direction to permit the switch points to move away fromtheir reverse positions is effectively blocked by the roller. It will beseen, therefore, that when the switch points occupy their reverseextreme positions, they are effectively held in these positions due tothe coaction between the roller and the escapement crank, and it willalso be seen that any force which may be exerted on the switch tendingto restore it to its normal position will cause a transverse force to beexerted on the rack bar rather than a longitudinal force, thus avoidingany tendency to reverse the handthrow lever due to any force which maybe exerted on the switch.

In order to restore the movable rails to their normal positions afterthey have been reversed as above described, the hand-throw lever 38 isrestored to the position in which it is shown in Fig. 1. The subsequentmovements of the parts under these conditions are just the reverse ofthose described above, and it is believed, therefore, that the operationof the apparatus under these conditions will be readily understood froman inspection of the drawings without further description.

I shall now assume that the parts are in their normal positions, asshown in the drawings, and that a train trails the switch. As theleading wheels of the train r011 along the fixed rail I and the movablerail 2a, the movable rails 2 and 2a are forced over laterally, butbefore a sufficient force is developed to overcome the opposing force ofthe spring connecting rod C and cause the point of the movable rail 2 tomove out of engagement with fixed rail l, the movable rails beingsomewhat resilient become bent, so that with the usual standard splitswitch, the tie rod 8 is moved upwardly, as viewed in Fig, 1, threequarters of an inch or more. This movement of the tie rod 8 actingthrough the switch basket 18, operating rod Tl, bell crank lever 75,link 14, turnbuckle T3 and plunger bolt Ill moves the piston 55 of thespring cage 54, and hence the lock bar 5|, in opposition to the bias ofthe spring 8| a suflicient amount to withdraw the lock bar 5| completelyout of engagement with the notch 48 in the lock rod L, thus unlockingthe switch. As a result, when the leading wheels have reached thepositions in which a suflicient force is developed to cause the point ofthe movable rail 2 to move out of engagement with the fixed rail I, theswitch points will be unlocked, and the points will therefore be forcedopen by the wheels in exactly the same manner as would be the case if nopoint lock were provided, and the buning device D will perform its usualfunction of preventing the movable rails from snapping back after thepassage of each wheel through them. When the train which is trailing theswitch has completely passed the switch, the movable rails will slowlyreturn to their normal positions under the bias of the spring connectingrod, and against the retarding force of the buffing device D. Dur ingthis return movement of the movable rails there will be no deflection ofthese rails, and the lock bar El will be moved into engagement with theside of the lock rod L before the movable rails have reached their fullnormal positions in which the lock rod. is in the proper position forthe notch 48 therein to receive the locking plunger. The spring 6! willtherefore become compressed, and will urge the lock bar 5| intoengagement with the side of the lock rod, until the notch 48 moves intoalignment with the lock bar, at which time the energy stored in thecompressed spring 6i will force the lock bar into place in the notch 48,thus restoring the switch to its normal locked condition. If the notch48 in the lock rod should not come into alignment with the lock bar, asuitable indication of this fact will be given by means of the circuitcontroller referred to hereinbefore.

During a facing point move, there is no lateral thrust on the movablerails corresponding to, or commensurate with, that which occurs during atrailing movement, and what lateral thrust there is will be in thedirection to permit the spring 6| to force the locking plunger furtherinto the notch 48 in the lock rod L.

It will be noted that when the parts are in their normal positions, asshown in Fig. 1, the reaction of the biasing spring BI is transmittedthrough the rack bar and segment gear 30 .to the hand-throw lever 38,which tends to raise this lever. However, this lever is so designed thatit has sufiicient weight to resist and overcome this reaction.Furthermore, if it is undesirable to provide the lever l3 withsufficient weight 'to overcome the reaction of the spring 6|, this levermay be held down by means of a conventional gravity lever latch stand,two of which stands are indicated at 9! in Fig. 1.

One advantage of switch operating apparatus embodying my invention isthat the construction of all of the parts are relatively simple and aresuch that they can readily be assembled and disassembled in service.

Although I have herein shown and described only one form of railwayswitch operating apparatus embodying my invention, it is understood thatvarious changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is:

1. The combination with a spring switch and a switch operating mechanismcomprising a casing containing a rack bar reciprocable between twoextreme positions and operatively connected with the switch for movingthe switch between its two extreme positions, of a lock bar slidablymounted in said casing above said rack bar and movable between a lockingposition in which it looks said switch in one extreme position and anunlocking position, a spring cage slidably mounted in said casing andoperatively connected at one end with said rack bar for movementtherewith and provided in one end with an opening through which saidlock bar extends into said spring cage with clearance, a piston in saidspring cage secured to said lock bar, and a spring in said Spring cageengaging said piston and effective when said rack bar occupies theposition corresponding to said one extreme position of said switch tobias said lock bar to its locking position.

2. The combination with a spring switch and a switch operating mechanismcomprising a casing containing a rack bar reciprocable between twoextreme positions and operatively connected with the switch for movingthe switch between its two extreme positions, of a tubular housingsecured to one end of said casing, a tubular spring cage slidablymounted in said housing and containing a reciprocable piston biasedtoward one end of said spring cage, means for securing said spring cageto said rack bar to move therewith comprising spaced arms provided onsaid one end of said cage and connected together by a depending webdisposed in a transverse slot provided in said motion plate, a lock barreciprocably mounted in said casing above said rack bar and extending atone end into said cage between said arms with clearance and secured tosaid piston, and means cooperating with said lock bar for locking saidswitch when said switch occupies said one extreme position and saidpiston occupics the position to which it is biased by said spring.

3. The combination with a spring switch and a switch operating mechanismcomprising a casing containing a rack bar reciprocable between twoextreme positions and operatively connected with the switch for movingthe switch between its two extreme positions, of a lock rod connectedwith the movable rails for movement therewith and provided with a notch,a lock bar adapted to enter the notch in said lock rod when and onlywhen the switch occupies its normal position to lock the movable railsin this position of the switch, said lock bar being movable within saidnotch to an extreme position which is beyond the normal lockingposition, a housing secured to one end of said casing, a spring cageslidably mounted in said housing and operatively connected at one endwith said rack bar to move therewith, a piston in said spring cageoperatively connected with said lock bar, a spring in said spring cageengaging said piston for biasing said lock bar to said extreme positionwhen said motion plate occupies the extreme position corresponding tosaid one extreme position of said switch, a tubular extension on saidpiston provided at its free end with an annular inturned shoulder, aplunger bolt extending into said tubular extension through clearanceholes in said housing and said spring cage and provided with a headcooperating with said shoulder, and linkage adapted to be mechanicallyactuated by a train trailing said switch connected with said plungerbolt, said linkage being so constructed and so adjusted that when saidswitch occupies its normal position said linkage will act through saidplunger bolt, said shoulder, said tubular extension and said piston. toprevent said locking plunger from moving beyond its normal lockingposition but that when a train trails the switch said linkage will actto withdraw said locking plunger from the notch in said lock rod tounlock the switch.

4. The combination with a spring switch and a switch operating mechanismcomprising a casing containing a rack bar reciprocable between twoextreme positions and operatively connected with the switch for movingthe switch between its two extreme positions, of a lock bar slidablymounted in said casing and movable between a locking position in whichit locks said switch in one extreme position and an unlocking position,a spring cage slidably mounted in said casing and operatively connectedat one end with said rack bar for movement therewith, and spring meansin said spring cage operatively connected with said lock bar andeffective when said rack bar occupies the position corresponding to saidone extreme position of said switch to bias said lock bar to its lockingposition.

KENNETH J. J MCGOWAN.

